Help - I've changed the default font of all posts

I was trying to change the font of the headings such as for the links etc because I wanted to change to a darker blue. So I went into widgets and tried putting the <font color="0000FF"> in the top of the links widget next to links. Now all it has done is changed my entire blog to blue. Every single post is now all blue. How can I change it back to the way it was?

I have solved the problem. User error! (Well maybe) My first widget was a subscribe widget which I had changed the font colour of the text to blue. This has had the effect of making my entire site blue. I don't know if this is a bug or by design. I would assume that changing the font color of the text in a widget would just apply to that widget but it doesn't from this example.
Cheers for the help Raincoaster. As ever, superb support.